Aim: 

To set up a method that permits the simultaneous recording of the blood vessel (BV) tone and ionic currents from endothelial cells (EC) located on the BV luminal surface, as an attempt to study the functional relationship between EC and smooth muscle cells (SMC).

Methods: 

Rat mesenteric arteries were mounted as ring preparations in a microvascular myograph. Vessel tone was recorded simultaneously to whole cell currents from EC under Patch Clamp technique. Neurobiotin was iontophoresed into the EC for identification purpose. Voltage pulses were applied to the recorded EC before and after 100 nM phenilephrine (Phe) and 10 mM Acetilcholine (ACh).

Results: 

ECs were homogeneously stained by neurobiotin. Outward potassium (K⁺) currents were recorded; K-current amplitude was decreased to 630.01% by Phe (P<0.05), and the effect was recovered by ACh (P<0.05). Simultaneously, Phe-induced an increased in the isometric force (P<0.0001), that was recovered by ACh (P<0.005).

Conclusion: 

Neurobiotin staining indicates that ECs are electrically coupled through gap junctions.The present method allows simultaneous recording of ionic currents 'in situ' and of the isometric force. Outward K⁺ currents recorded from EC may come through gap junctions, at least in part, from the SMC.

Supported by M.E.C., Grant No. BFU2007-67732/BFI.